Continuous flow expander for expanding particulate material

ABSTRACT

A continuous flow expander for expanding particulate material, more specifically for grain or cattle fodder, is provided whereby material to be expanded is transported in a substantially continuous manner through a pressurized region wherein it is heated, steamed and pressurized by a counterflow of dry steam created from available city water by a recirculating steam boiler. The material is then ejected by another flow of dry steam created from available water into a lower pressure region for expansion. Enthalpy in the ejection region is automatically maintained within a predetermined range, for grain or cattle fodder from 450 to 750 BTU per pound of moisture being ejected, regardless of the moisture content of the material, by varying steam boiler output and, if necessary, material flow rate. An expanded product requiring no further drying prior to use or storage is thereby provided with minimum energy use.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to the field of expansion of particulatematerial capable of expansion by rapid internal decompression withoutsubstantial disintegration. More particularly, it relates to expansionof grain or cattle fodder, wherein grain or fodder is heated, steamedand pressurized and is then ejected into a lower pressure region whereit rapidly decompresses into a much expanded form, whereby physical andchemical properties are beneficially altered.

2. Description of Prior Art

Various processes and apparatus have been developed over the past fewdecades for modifying or converting cereal grain into a form morereadily consumable by humans, typically into some form of breakfastfood. These include processes for converting cereal grain into a flakeform, like corn flakes, by steaming and then rolling or flaking it, orinto a puffed form, like puffed wheat, by steam pressurizing the grainand then ejecting it into a lower pressure region where it explosivelydecompresses into a much expanded form (for example, U.S. Pat. Nos.2,622,985; 2,698,799 and 2,838,401 for puffing cereal grains). Stillother processes employ pressure cooking to partially or fully cookstarchy grains such as rice (for example, U.S. Pat. Nos. 2,525,137;2,758,031; 3,085,011 and 3,085,013).

More recently, attempts have been made to adapt such processes totreating fodder material for cattle (the term cattle as used herein alsoincludes other types of livestock and the term fodder as used hereinincludes various types of grain). The principal objective is to reducefeed costs, particularly at large feed lots, by creating an altered ormodified fodder from which cattle can extract more nourishment. Itappears this can be accomplished by irreversibly breaking down the largemolecules of relatively hard to digest starch in the fodder into smallermolecules of more easily digested dextrin.

Initially the fodder treatments involved either pressure cooking thefodder or steaming and then rolling or flaking it. However, the maximumbenefit sought was not achieved because the conversion of starch intodextrin by these processes is largely reversible. As a consequence, atleast some of the dextrin reconverts to starch before the animal'sdigestive process begins.

In 1972, Algeo (U.S. Pat. No. 3,667,961) described a batch process forirreversibly breaking down the starch in fodder materials into dextrin.This process, similar to those used for puffing cereal grains, includedpressurizing the fodder in a steam atmosphere at moderately hightemperatures for a short period of time before ejecting it into theatmosphere where the pressurized particles explosively depressurizedinto a much expanded form. In theory, the steaming softens the fodderparticles and allows them to become internally pressurized, and thesubsequent explosive depressurization physically ruptures chemical bondsin the starch molecules, thereby irreversibly breaking down the starchmolecules into dextrin molecules. Algeo described several side benefitsincluding (1) increased porosity of the expanded fodder which allowseasy penetration of the livestock's digestive juices, (2) thermaldecomposition into harmless form of most chemical pesticides which mayhave been used on the fodder, and (3) destruction of any weed seed inthe fodder, thereby providing for a weed-free manure.

This fodder expansion process appears to have achieved promising resultsin small scale practice and was given wide publicity, a feed costreduction of from six to nine dollars per head of cattle being thenestimated. (The estimated savings per head is currently about nineteendollars.) However, for numerous reasons to be examined, the results inactual use have not lived up to expectations.

The principal use of fodder expanders is at centralized feed lots wherelarge numbers of cattle are gathered to be fattened for market. Thesefeed lots contain tens or hundreds of thousands of cattle which consumevast quantities of fodder (approximately 24 pounds per head of cattleper day). Location of the fodder expansion apparatus in the immediatevicinity of the feed lots is essential to avoid the prohibitive cost ofshipping such quantities of bulky expanded fodder. The apparatus mustthus be used in a field, as opposed to a laboratory or factory,environment and is located in relatively remote regions where equipmentservicing is expensive and inconvenient and where well trained operatingand maintenance personnel are unlikely to be found. Another economicfeasibility requirement is that the expansion apparatus must be insubstantially continuous operation to meet the fodder demands. It musttherefore be extremely reliable.

Fodder expansion apparatus heretofore used have, to the contrary, provenquite unreliable. A major reason for this unreliability relates to thefact that satisfactory means has not previously, to the applicant'sknowledge, been developed for introducing the untreated fodder into thepre-expansion pressurizing region without first depressurizing theregion; that is, only batch expanders have as yet been employed. In abatch expander, the pressure vessel in which the fodder is heated andpressurized is first filled with fodder and then pressurized with steam.After a short pressurization period, the fodder is ejected to theatmosphere for expansion. The vessel must be vented before another batchof fodder is introduced and then repressurized before processing of thenew batch is commenced. To compensate for lost vessel-filling time inorder to achieve reasonable flow rates of fodder through the apparatus,the pressurization period is generally made quite short -- typicallyonly about 15 to 20 seconds -- representing only a fraction of theentire batch cycling time. This short pressurization period, because ofthe relatively large, stationary mass of fodder, generally results ininadequate pressurization of a significant amount of the fodder, withthe result that these under-pressurized particles do not subsequentlyexpand sufficiently to convert all the starch to dextrin. To furthercompensate for lost vessel-filling time, fodder particles are generallytransported through the apparatus at high velocity. Because of theabrasiveness of the fodder, rapid internal wear of the apparatus,particularly in regions (such as elbows) of abrupt direction change,results and frequent shutdowns are necessary to replace eroded parts.

Still other problems relate to the general use of large quantities ofhigh quality, that is, dry, boiler steam for heating and pressurizingthe fodder and for ejecting it to the atmosphere. Further, the cyclicventing of the pressurized vessel causes moderate losses of high energysteam and is therefore wasteful not only of the boiler feed water fromwhich the steam is created, but also of the energy used to create thesteam. This large consumption of boiler steam by existing equipment hasnecessitated installation at feed lots of extensive water softeningfacilities for producing boiler feed water. This not only results inadded expense, but problems associated with the water softening systemshave frequently caused shutdown of the entire expansion apparatus.

Another major problem has been that the expanded fodder generallyrequires auxiliary drying before handling or storage because of its highwater content. This is because the moisture initially present in thefodder -- typically twelve to fifteen percent by weight -- operates asan energy sink and absorbs so much energy from the pressurizing and theejecting steam that some of the steam is condensed into water. When thiswater is ejected with the fodder, it is absorbed by the expanded fodder,causing the expanded fodder to be too wet to be easily handled orstored. In order to produce, by present expansion processes andapparatus, an expanded fodder sufficiently dry for handling or storage,steam boiler horsepower would have to be increased several fold.Generally, as an alternative to increasing boiler horsepower, largeauxiliary dryers are used to dry the expanded fodder, thereby stillgreatly increasing system complexity and cost.

A problem of increasing significance is the high noise level produced bythe expansion process. The explosive decompression of the material isnot the sole noise source. Considerable noise is produced by supersonicexpansion of the high pressure steam leaving the ejection opening ornozzle. When the ejection region is full of fodder, the steam expansionnoise is attenuated to some extent; however, in batch processing thereare frequent periods when there is an outflow of expanding steam withthe ejection region virtually empty of fodder, and thus there is nonoise attenuation. Also, no attention has previously been directed tothe fact that the nozzles or restrictive openings used at the ejectionpoint have subsonic characteristics, whereas the steam expansion isgenerally supersonic.

An object of this invention is to provide an improved apparatus forexpanding fodder material whereby the desired beneficial results may beachieved with minimized deficiencies such as above described. To thisend, a continuous flow fodder expander is provided which recirculatesboiler steam to create heating, pressurizing and ejecting steam fromuntreated city water and which automatically maintains a predeterminedejection region enthalpy regardless of moisture content of the fodder,in order to insure a dry expanded product.

The system to be described, with relatively low fuel flow and withoutrequiring superheat, obtains a consistent lightweight product having lowmoisture content. It can handle different grains on an individual basisand is capable of processing high bulk density products that areresistant to flow. The system is more efficient than known steamprocesses in that it processes more grain for the same system inputenergy or can produce higher nozzle enthalpy with the same productweight per unit of time. The system is automatically controlled tohandle the particular product and is also adjustable to handle differentproducts of different bulk density.

Other objects will be apparent from the description and the appendedclaims.

SUMMARY OF THE INVENTION

The apparatus of the present invention, according to a preferredembodiment, comprises means for, introducing fodder material to beexpanded into a pressurized region while maintaining substantialpressure in this region, transporting the material through thispressurized region in a substantially continuous manner to an ejectionregion, and ejecting the material through a restrictive opening ornozzle (preferably a supersonic nozzle) into a lower pressure regionwhere the material expands into puffed form.

Stated more specifically, a recirculating steam boiler creates highenthalpy, dry steam from available water for heating, steaming andpressurizing the fodder material in the pressurized region. A largediameter screw transports the material through a reactor in thepressurized region in a direction opposite to the flow of steam so as toachieve optimum enthalpy transfer from the steam to the material.Additional enthalpy is added to the material by a second flow of drysteam, also created from available water, which ejects the material intoa low pressure expansion region.

To insure a dry expanded product with minimum energy use, the enthalpyat the ejection region is maintained within a selected range (forlivestock fodder preferably 450 to 750 BTU per pound of moisture beingejected in the form of steam, water and moisture in the fodder material)regardless of initial moisture content of the material, by automaticcontrols which maintain a predetermined pressure, related to nozzleenthalpy, in the pressurized region. This controlling is accomplished byvarying steam boiler enthalpy output and, if necessary, by varying theflow rate of the fodder material into the pressurized region.

BRIEF DESCRIPTION OF THE DRAWINGS:

FIG. 1 is a block diagram showing major portions of the fodder expander;

FIG. 2 is a schematic drawing of the apparatus of FIG. 1;

FIG. 3 is a vertical section of the fodder injector showing itsconstruction and its cavity in the filling position;

FIG. 4 is a vertical section of the fodder injector showing itsconstruction and its cavity in the emptying position;

FIG. 5 is a vertical section of the fodder injector showing itsconstruction and its cavity in the venting position;

FIG. 6 is a schematic drawing showing control of the boiler fuel valveand the injector hydraulic pressure regulator;

FIG. 7 is a vertical section of a variation of the fodder injectorshowing two cavities, one filling while the other is emptying;

FIG. 8 is a partial schematic of the automatic boiler fuel valvecontrol;

FIG. 9 is a vertical section of the supersonic nozzle; and

FIG. 10 is an enlarged view of pressurized Region B as shown in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT

By way of introduction, and as diagrammed in FIG. 1, fodder material tobe expanded is introduced through, and by, an Injector A into aPressurized Region B. As the fodder is transported in a continuousmanner through Pressurized Region B, it is heated and steamed by acounterflow of high enthalpy, dry processing steam from a Steam SourceC. (Enthalpy is a thermodynamic expression for thermal potential of avapor system in flow, comprising an internal energy term and a termrelating to the pressure and volume of the system.) This processingsteam also provides the pressurizing for Pressurized Region B and isinstrumental in introducing the fodder into the Pressurized Regionthrough the Injector.

From the Pressurized Region, the fodder is transported to a NozzleRegion D where it is ejected by a flow of high enthalpy, dry ejectionsteam from steam Source C into the atmosphere for expansion.

Enthalpy in Nozzle Region D is controlled within a predetermined rangeby Automatic Control E, to assure dryness of the expanded fodder. Nozzleenthalpy, supplied by the processing and ejecting steam flows from SteamSource C, is automatically controlled within the predetermined range,regardless of the initial moisture content of the fodder, by sensing andcontrolling a corresponding pressure in Pressurized Region B. Thispressure is an accurate and sensitive measure of nozzle enthalpy,decreasing as nozzle enthalpy decreases and increasing as nozzleenthalpy increases.

Automatic Control E maintains the pressure in the Pressurized Regionwithin a predetermined range by first varying the enthalpy output of theSteam Source (an increase or decrease in enthalpy from the Steam Sourcecauses a corresponding increase or decrease in Pressurized Region Bpressure) by varying fuel flow to a steam boiler in Steam Source C. Ifthe predetermined pressure cannot be maintained by so doing, the flowrate of fodder material into Pressurized Region B through Injector A isvaried, such that there is less or more fodder moisture moving throughPressurized Region B to absorb enthalpy from the steam, therebycorrespondingly increasing or decreasing the pressure in PressurizedRegion B.

For convenience, the ensuing description of a preferred embodiment isdivided into the general headings just mentioned and shown in FIG. 1;however, the order is changed for purposes of clarity.

The described preferred embodiment provides primarily for processing themore commonly used fodder grains, such as corn, barley and milo.Variations applicable for processing lower density fodder materials,such as chopped hay or straw, will be provided at the appropriate place.

PRESSURIZED REGION B

The essential function of heating, steaming and pressurizing the fodderprior to its ejection into the atmosphere for expansion into puffed formis performed in Pressurized Region B, which comprises severalcommunicating components, as seen in FIGS. 2 and 10, all of which are atsubstantially the same high pressure.

The fodder to be expanded is injected into a pressurized separator 5 bya flow of high enthalpy, dry steam (herein referred to as processingsteam), passing through Injector A to be described below. In separator5, which is closed except for a steam and fodder inlet pipe 6, a fodderoutlet metering valve 7 and a steam outlet pipe 8, the fodder and steamare separated by a disengaging process so that they may later flowcounter to each other for optimum enthalpy transfer to the fodder. Thefodder entering via pipe 6 falls by gravity to the conical bottom of theseparator, from which it is fed by metering valve 7 (for example, aconventional star valve), into a downwardly curved pipe 9. The fodderthan falls by gravity through pipe 9 into the lower side of acylindrical reactor 10. Within reactor 10, to be more fully describedbelow, the fodder is upwardly transported in a continuous manner towarda fodder outlet pipe 11, by a large rotating screw 12. During thistransport through the reactor, the fodder is subject to a counter, ordownward, flow of pressurizing steam from separator 5, which enters thetop of reactor 10 via a steam pipe 8 interconnecting the separator andthe reactor.

As the upwardly transported fodder in reactor 10 reaches the level offodder outlet pipe 11 near the top of reactor 10, a portion of thefodder is deflected by a rotating deflector vane 13 into the outletpipe, through which the fodder falls by gravity into Nozzle Region D.Region D comprises a metering valve 14, which transports the fodder toan ejection pipe 15 from which it is ejected to the atmosphere forexpansion into puffed form.

More specifically, the separation of the incoming fodder and processingsteam in separator 5 is accomplished by requiring the processing steamflow to change direction abruptly before exiting the separator. Theprocessing steam is thereby prevented from carrying with it quantitiesof fodder as it leaves pipe 8.

To accomplish disengagement, inlet pipe 6, axially affixed to theotherwise closed top of separator 5 as by welding, has an open lower endwhich extends well below the opening to steam outlet pipe 8 which islocated near the top of the separator. Inlet pipe 6 contains numerousholes through its side near its open lower end below the separatoropening to pipe 8 so that the processing steam starts separating fromthe fodder within pipe 6. When the processing steam leaves pipe 6through either the side holes or the open bottom, it must changedirection and flow up towards the top of the separator to reach theopening to outlet pipe 8. As a result of directional changes, the fodderparticles fall from the steam flow to the bottom of the separator. Onlya minimal quantity of processing steam, that which fills the voidbetween fodder particles, flows along with the fodder through meteringvalve 7.

The disengaging action described above is generally adequate for theheavy, more commonly used fodder materials, such as corn, barley andmilo. Additional disengagement may be required for lighter foddermaterials, such as chopped hay or straw. If use of such lighter foddermaterials is anticipated, baffles may be installed in separator 5 tocause the flow of processing steam to make more directional changes. Thesize of separator 5 may also be increased over the size suitable forheavier fodder materials if lighter materials are to be processed in thesame apparatus.

To provide additional disengagement in separator 5 for lighter foddermaterials, a tubular inner baffle 16, open at both upper and lower ends,is axially supported within separator 5, as by being attached to thelower conical portion and sides of the separator, with its lower endbelow the normal fodder level at the bottom of the separator. Steam flowaround the bottom of baffle 16 is thus blocked. The upper end of baffle16 is near, but spaced from, the top of the separator to allow steamflow over baffle 16. A tubular outer baffle 17 depends coaxially aroundinner baffle 16 from the top of separator 5, its open lower end beingsubstantially below the separator opening to pipe 8 through which theprocessing steam exits the separator. To exit separator 5 via pipe 8,processing steam entering the separator with the fodder via inlet pipe 6must first flow upward from the bottom of pipe 6 and over the top ofinner baffle 16. The steam must then flow downward and under the bottomof outer baffle 17 before it again flows upward towards outlet pipe 8.By this means additional disengagement is provided for the lightweightfodder materials.

Although the fodder and processing steam enter separator 5 via pipe 6together in parallel flow, there is relatively little enthalpy transferfrom the steam to the fodder because of the short intermingling timebefore they are separated, the fodder falling to the bottom of theseparator and leaving through valve 7, and the processing steam, afterdisengagement, leaving via pipe 8. Substantially all of the enthalpyinterchange from the processing steam to the fodder occurs in reactor 10wherein there is a counterflow, rather than a parallel flow, of fodderand processing steam.

Reactor 10 comprises a large pressurized vertical cylinder, closedexcept for steam inlet pipe 8, a steam outlet line 18, fodder inlet pipe9 and a fodder outlet pipe 11. The inner diameter of reactor 10 issubstantially larger than the outer diameter of screw 12 which iscoaxially mounted within the reactor and which transports the fodder upthrough the reactor from inlet pipe 9 to outlet pipe 11. Because of thespacing between the screw and the reactor and their verticalarrangement, some of the fodder being upwardly transported by screw 12falls off the edges of the screw back toward the bottom of the reactorfor recirculation. Deflector vane 13, rotating with screw 12, both beingnonrotatably mounted on a common shaft 19 driven by a motor 20, as by asystem of gears (not shown), deflects many of the fodder particlesreaching the level of outlet pipe 11 to the inner side of the reactorwhere they too fall back down for recirculation. This continuousrecirculating assures that virtually all fodder particles receiveuniform and adequate heating, steaming and pressurizing, as required foruniform and optimum expansion.

The rotational speed of screw 12 determines the average transit time offodder particles through reactor 10. To maintain a constant mass flowrate through the reactor, screw 12 may be rotated faster, to increasethe bulk flow rate through the reactor, for less dense fodder materials,and may be rotated slower, to reduce the bulk flow rate through thereactor, for more dense material. The rotational speed may be varied bya conventional gear connection (not shown) between shaft 19 and motor20.

The counterflow of processing steam and fodder within reactor 10 isnecessary for optimum heating, steaming and pressurizing of the fodderto assure a uniform, well-expanded product. During this counterflow,much of the processing steam enthalpy is absorbed by the fodder and itsinitially included moisture, as the former is raised to the temperatureof the steam and the latter is raised to the boiling point of water. Theprocessing steam, flowing axially downward from pipe 8 at the top ofreactor 10, is driest and at its highest enthalpy level when it isflowing past the fodder particles which are deflected from rector 10into pipe 11, and is wettest and at its lowest enthalpy level as itflows past the fodder particles just entering the bottom of reactor 10through pipe 9. The processing steam then exits the reactor bottom vialine 18, after passing through a rotating screen 21, driven by a motor22, to prevent fodder being carried along with the exiting steam.Processing steam is otherwise prevented from exiting reactor 10 alongwith the fodder through pipe 11 by valve 14, through which only aminimal amount of steam exits between the fodder particles.

INJECTOR A

Injector A performs the critical function of introducing, or injecting,fodder material from a source of fodder at low or ambient pressure intoPressurized Region B (or, as described above, into separator 5 via pipe6), while pressure is maintained in the Pressurized Region andprocessing of previously introduced fodder continues in an uninterruptedmanner. In this respect, Injector A may be considered a conveyor whichtransports fodder material from a source to the Pressurized Region B.

The injector, as best seen in FIGS. 3, 4 and 5, comprises a horizontalpiston sleeve or cylinder 26, which is cylindrical and may be termed achamber. The sleeve is attached toward one end, as by welding, to thebottom of a fodder hopper 27, which hopper is generally conically shapedand is positioned vertically above sleeve 26 for gravity feed of fodderthereinto. A first opening 28 in the sleeve, registered with hopper 27,provides communication between the bottom of the hopper and an intakeregion of the sleeve. Sleeve 26 is also attached towards its oppositeend, for example by welding, to the upper end of the pipe 6 whichconnects to separator 5. A second opening 29 in sleeve 26, in line withpipe 6, provides communication between such pipe and the dischargeregion of the sleeve.

The sleeve 26 has axially mounted therein a conveyor comprised of twoaligned pistons, both preferably made of generally the same metallicmaterial as sleeve 26. The first piston 30 has a constant or uniformoutside diameter, being installed at the hopper end of sleeve 26. Thesecond piston 31 is spool-shaped and is mounted at the separator end ofthe sleeve. Pistons 30 and 31 are shown as being hollow but have closedor solid ends relatively adjacent each other. The closed piston ends arespaced apart on a common shaft 32, to create a chamber or cavity 33defined by the adjacent closed piston ends and by the inside surface ofsleeve 26. The axial length of cavity 33 is preferably, but notnecessarily, substantially the same as the diameter of openings 28 and29 in the sleeve. Pistons 30 and 31 are fixed together and maintained intheir spaced relationship as by plural lock nuts 34 on shaft 32,installed on both sides of the adjacent piston ends.

Conjoint axial movement of pistons 30 and 31 in sleeve 26 isaccomplished by a hydraulic actuator 35 (FIGS. 2 and 6) which isattached at one end of shaft 32. Movement of the pistons by actuator 35is such as to first register cavity 33 with hopper 27 for gravityfilling with fodder, and then with pipe 6 for emptying the fodder intoseparator 5.

The relationship between the length of piston 31 and the spacing betweenhopper 27 and pipe 6 is such that, as shown in FIG. 3, when cavity 33 isbeing filled with fodder from hopper 27, opening 29 to pipe 6communicates with the annulus surrounding spool piston 31. A steam inletline 36 is attached to sleeve 26 in axial alignment with pipe 6, andthen communicates via a third opening 37 with the indicated annulus.Line 36 provides a full flow of processing steam into sleeve 26, aroundthe annulus region of piston 31 and into separator 5 through pipe 6,separator 5 being at a slightly lower pressure than the processing steampressure at inlet line 36 due to the pressure drop across the injector.In this cavity filling position, pressure escape from separator 5 andsteam inlet line 36 to the atmosphere around the left end of piston 31away from cavity 33 is prevented by plural, preferably at least three,piston rings 38, installed in that larger outer diameter end of piston31. Pressure is similarly prevented from escaping around the cavity endof piston 31 by plural, preferably at least three, piston rings 39installed in that larger outer diameter end of piston 31.

The length of piston 30 is such that when, as depicted in FIG. 4, cavity33 is aligned with pipe 6 for emptying fodder into separator 5, opening28 to hopper 27 is completely sealed by the outer diameter of piston 30,thereby preventing unwanted fodder discharge into the sleeve. Whencavity 33 is aligned with pipe 6, processing steam from line 36 flowsdirectly through cavity 33 and pipe 6 into separator 5, thereby sweepingthe fodder from the cavity into the separator to provide rapid andvirtually complete discharge from the cavity. Escape of the steam fromthe cavity region is prevented by the piston rings 39 on piston 31 andby similar plural, preferably at least two, piston rings 40 installedtoward the cavity end of piston 30.

A steam vent line 41, attached to sleeve 26 as by welding, andcommunicating with the inside of sleeve 26 via a fourth opening 41a, ispositioned between openings 37 and 28 and vents pressure from cavity 33after the cavity is out of communication with steam inlet line 36 andpipe 6 where it becomes pressurized, and before it recommunicates withhopper 27 (FIG. 5). Therefore, when the cavity comes back into alignmentwith the hopper, there is no cavity pressure to retard filling or toblow fodder from the hopper.

Actuator 35, for pistons 30 and 31, as schematically shown in FIG. 6, isoperated by hydraulic pressure in either of two hydraulic lines 42 and43 which enter at opposite ends of the actuator. Pressure from ahydraulic line 44 is shunted between lines 42 and 43 by an electricallycontrolled solenoid valve 45 connected thereto. Valve 45 is controlledas by two electrical microswitches 46 and 47 located at opposite ends ofpiston sleeve 26 and actuated by pistons 30 and 31 at their extremepositions of travel. At one extreme of piston travel (cavity 33 alignedwith hopper 27 for filling) the end of piston 30 away from the cavitycloses a contact on microswitch 47 to signal valve 45, via an electricalline 48, to shunt hydraulic pressure from line 42 to line 43, therebyreversing actuator piston travel and moving the cavity away from thehopper and toward pipe 6. In an analagous manner, at the other extremeof travel (cavity 33 aligned with pipe 6 for discharging), the end ofpiston 31 away from the cavity closes a contact on microswitch 46,thereby directing valve 45, via an electrical line 49, to shunthydraulic pressure back to line 42 to again reverse actuator pistontravel and move the cavity back toward the hopper for refilling. By thismeans, cyclic action of the cavity is achieved, the cycling rate, aslater discussed in more detail, being variable according to thehydraulic pressure supplied to actuator 35--the higher the hydraulicpressure, the faster the cavity cycling rate.

Because of the relatively low velocity of piston 30 and 31 travel(normally only about 28 cycles per minute for the preferred embodiment)no lubrication is required between the injector parts in slidingcontact, that is between piston rings 38, 39 and 40 and the inside ofpiston sleeve 26, it being generally sufficient that the inner surfaceof sleeve 26 have a smooth, hard surface, such as provided by hardchrome plating, and that the piston rings be of some metallic materialsuch as iron or steel.

In a variation of the preferred embodiment, shown in FIG. 7, anadditional constant (uniform) diameter piston 30a, similar to piston 30,is installed on shaft 32, as by lock nuts 34a, its closed end separatedfrom the end of a solid spool piston 31a (similar to spool piston 31,except that it has two closed ends) which is away from piston 30. Asecond cavity 33a is thereby created between piston 30a and piston 31a.The piston configuration is such that when cavity 33 is aligned foremptying into pipe 6, the emptying being assisted by a flow ofprocessing steam from line 36, cavity 33a is aligned for gravity fillingfrom a second material source or hopper 27a. Similarly, when cavity 33is aligned for gravity filling from hopper 27, cavity 33a is positionedfor emptying into pipe 6. In this manner, two different materials fromdifferent sources may alternatively be introduced into the samepressurized region at different rates, assuming different cavity sizes,or the same material may be injected at an increased rate from twodifferent hoppers. An additional vent line 41a, similar to vent line41', is provided to vent cavity 33a in the same manner as describedabove for cavity 33.

STEAM SOURCE C

It is common knowledge that when sufficient energy in the form of heatis supplied to water, its temperature will be raised to the boilingpoint (212° F.), and the water will be converted into steam. Such steamis normally comprised of a mixture of moist vapor and dry gas, only themoist vapor being visible to the eye. As more heat is applied to thesteam, more of its moist vapor will be converted to dry gas. Inthermodynamic parlance, the "quality" of the steam increases as itbecomes more gaseous or dry. When sufficient heat has been applied, allof the moist vapor in the steam will be converted to dry gas, and thesteam will be of 100% quality. At ambient pressure, this occurs at 212°F. As still more heat is applied, the temperature of the dry steam willbe raised above 212° F., the steam becoming superheated.

The process described above is reversed as heat is absorbed from thesteam. The steam gradually becomes moister, that is its quality isreduced, until at last the steam contains only moist vapor. In thiscondition, the steam is said to be of zero percent quality. As stillmore heat is absorbed from the steam, its temperature begins to fallbelow 212° F., and some of the wet steam condenses into water. At thispoint, the steam is said to have a quality level below zero. This latteris commonly observed when steam impinges upon a cooler object anddroplets of condensed water form on the surface of the object.

Processing Steam

In the preferred embodiment, dry, preferably saturate (i.e.,non-superheated) steam with high enthalpy (that is, steam with highinternal energy and pressure) is provided to steam, heat and internallypressurize the fodder particles prior to their expansion into puffedform.

The fodder particles and the moisture initially present in the fodder asit is introduced into the expansion apparatus are at ambient temperatureand are thus cooler objects against which the processing and ejectionsteam are directed. In raising the temperature of the fodder and itsmoisture, the fodder absorbs heat, or more accurately enthalpy, from thesteam being used to pressurize and eject it. Depending upon the relativemass flow rate of the fodder and the processing and ejection steam, themoisture content of the fodder, and the quality and enthalpy of thesteam, so much enthalpy may be absorbed from the steam by the fodder andits moisture that some of the steam may be condensed into water. Whensuch condensation occurs and the water is ejected with the fodder intothe expansion region, much of the water will be absorbed by the expandedfodder, making it wet and difficult to handle or store.

To prevent such occurrence, it is necessary to maintain the enthalpy atthe fodder ejection region at a sufficiently high level to assure thatthe quality level of the steam passing through the nozzle, in the formof ejection steam and moisture in the fodder which has been convertedinto steam, does not fall below zero. To this end, the preferredembodiment uses one flow of high enthalpy, dry steam, referred to asprocessing steam, to heat, steam and pressurize the fodder. And, ratherthan use this same steam with reduced enthalpy and quality to also ejectthe fodder, a second flow of high enthalpy, dry steam, referred to asejection steam, is used to eject the pressure fodder into the expansionregion.

Further, to avoid consumption of large quantities of boiler feed waterwhich is required to be softened to prevent boiler scaling, as whenboiler steam is directly used for processing and ejection, boiler steamis not consumed, but is used only to generate, by means of heatexchangers, a "secondary" source of steam from available untreated cityor tap water, herein referred to as city water. It is this secondarysteam that is employed to process the fodder and to create the ejectionsteam as described below.

Referring to FIG. 2, boiler feed water from a tank 60 is supplied by awater pump 61, via water lines 62 and 63, to a high efficiency steamboiler 64, wherein the feed water is converted into steam, hereinreferred to as boiler steam, by heat supplied by the boiler.

Boiler steam is routed from the boiler by a steam line 65 to a vaporizer66 which may be, for example, a heat exchanger of conventional tube andshell design, wherein a supply of available city water is converted byboiler steam into low quality secondary steam employed for fodderprocessing. Production of low quality secondary steam in vaporizer 66prevents precipitation in the vaporizer of impurities which may becontained in the untreated city water, which precipitation wouldadversely affect the characteristics of the vaporizer.

The boiler steam, with reduced enthalpy, is next routed from vaporizer66, via a steam line 67, through a pressure valve 68, which maintainsboiler steam pressure in the vaporizer, and via a steam line 69 to aconventional heat exchanger 70. In heat exchanger 70, the remainingboiler steam enthalpy preheats the city water prior to its conversion tosteam in vaporizer 66, as described above. The boiler steam, largelyreconverted to water within heat exchanger 70 by the enthalpy absorptionof the city water, exits heat exchanger 70, via water line 71, and flowsthrough a pressure valve 72, which maintains boiler steam pressure inheat exchanger 70, and a water line 73 back to tank 60, from which it isagain recycled through boiler 64. In this manner boiler steam iscompletely circulated with consumption only of its enthalpy in thecreation of a secondary source of steam for processing the fodder.

The city water from which the secondary source of steam is created issupplied by a pump 74 from any available source, such as a water main(not shown), via water lines 75 and 76 to heat exchanger 70, wherein, asabove-described, it is preheated by the boiler steam. The preheated citywater is routed from heat exchanger 70, via a water line 77, to thelower region of a drum separator 78, more particularly described below,the discharge from line 77 being below the water level of preheated citywater maintained in the separator. Preheated city water is next pumpedfrom the bottom of drum separator 78 by a pump 79, whose pumping ratemaintains the water level in drum separator 78, via water lines 80 and81, to the bottom of vaporizer 66 wherein, as previously described, thepreheated water is converted to low quality secondary steam.

From vaporizer 66, the low quality secondary steam created therein isrouted, via a steam line 82, to the upper region of drum separator 78 (alarge cylindrical tank), where it radially enters above the level of thepreheated water therein. The incoming steam impinges upon a baffle 83, alarge diameter, hollow cylinder, axially supported, in a manner notshown, from the inside top of the drum separator such that its openupper end is near the top of the drum separator and its lower end isbelow the level of the preheated water in the bottom of the separator,communicating therewith via a short pipe 84 which extends axiallydownward from the bottom of the baffle.

To exit the drum separator, via a steam line 85 at the top of theseparator, the incoming low quality secondary steam from vaporizer 66must flow upward and over the top of baffle 83, then down into thebaffle toward the surface of the preheated city water in the bottom ofthe drum separator, and then up and out the inner end of line 85 whichprojects axially down into baffle 83. These abrupt changes in directionof steam flow reduce the velocity of the steam to below the disengagingvelocity of the moist vapor in the steam; consequently, the moist vaporseparates from the dry gas in the steam and falls to the bottom of thedrum separator where it adds to the preheated city water. By this means,the quality of the incoming steam is substantially increased withoutloss of enthalpy, the exiting steam being of high, preferably 100percent, quality, and preferably being saturated rather than superheatedbecause such saturated steam is less expensive to produce than thesuperheated steam used in prior batch expanders and is less harmful tothe fodder (per Algeo).

The high quality processing steam is routed from separator 78 via line85 to steam line 36 at sleeve 26 of the fodder injector, and thence intoseparator 5 and reactor 10 where, as described above, it is used toheat, steam and pressurize the fodder prior to its expansion into puffedform.

Ejection Steam

The above-described processing steam, as it leaves the bottom of reactor10 via line 18, after having steamed and heated the fodder therein,still has considerable enthalpy, but its quality level will have beenreduced to such a low level that it is too wet to be directly used forejecting the fodder from the nozzle region. This steam still has,however, sufficient enthalpy to create a new, lesser flow of highquality ejection steam.

To this end, as seen in FIG. 2, processing steam exiting reactor 10 isrouted from reactor 10, via line 18 and a connecting steam line 86, to aconventional heat exchanger 87 wherein steam for ejecting the fodderfrom the nozzle region, or so-called ejection steam, is created from athird source of available water entering heat exchanger 87 via a waterline 88. High quality ejection steam is directly created in heatexchanger 87 without use of a disengaging drum, such as drum separator78. Because the flow of ejection steam is relatively low, there islittle scale buildup in heat exchanger 87. This third source of waterfor the ejection steam may be city water supplied to heat exchanger 87by pump 74, via water line 88. The ejection steam water mayalternatively be supplied from processing steam condensate which exitsheat exchanger 86 via a water line 89, through a pressure regulatingvalve 90. Pressure regulating valve 90 acts as a flow restrictor to helpmaintain pressure in reactor 10 and to prevent fodder packing in reactor10 during start-up. It does this by sensing the pressure drop acrossboth the reactor and heat exchanger 87, and maintaining it within apredetermined range, preferably two to three psi, by opening or closingto increase or decrease steam flow through the reactor and heatexchanger. The processing steam condensate will have been appreciablysoftened by the impurities initially present in the processing steambeing precipitated on the fodder particles. A portion of thiscondensate, after filtering, may be directed by a water line 91 to heatexchanger 87 where its use as a source of water for the ejection steamwill largely prevent any scaling of the heat exchanger which mightotherwise occur.

The dry, preferably saturated steam created in heat exchanger 87 isrouted via steam line 92 directly to metering valve 14 where, asdescribed below, it ejects the fodder into the atmosphere whereexpansion into puffed form occurs.

NOZZLE REGION D

After the fodder has been transported, heated, steamed and pressurizedin reactor 10 it falls under gravity through pipe 11 into metering valve14 wherein it is transported into alignment with pipe 15, as seen inFIG. 2. The fodder is ejected from pipe 15 to the atmosphere wherefodder expansion occurs, through a restrictive opening 93, preferably asupersonic nozzle, by a flow of ejection steam from line 92.

Restrictive opening 93, as mentioned, preferably comprises a supersonicnozzle wherein the ejection steam may expand supersonically to minimizenozzle noise. As seen in FIG. 9, the supersonic nozzle 93 comprises ashort region 94 converging to a throat 95. From throat 95, a long region96 diverges to an outlet opening 97, the ratio of the diameter of outletopening 97 to that of throat 95 preferably being on the order of 3:2 toprovide for the supersonic expansion within the nozzle, although thisratio may vary according to the pressure and flow rate of the steam anddensity and flow rate of the fodder material.

Although the supersonic nozzle may be made of circular cross-section, itis preferably rectangular in cross-section, with hinges at points 100and 100a and at 101 and 101a, whereby at least one cross-sectionaldimension of throat 95 and outlet 97 may be varied so that thecharacteristics of the nozzle may be changed to conform to variations insystem parameters.

Metering valve 14 is of conventional design and comprises a pluralsectioned star valve similar to metering valve 7 at the fodder outlet ofseparator 7 and is driven by a motor 102. Internal sealing, not shown,of conventional means, prevents internal steam leakage from pipe 11 topipe 15, the former being at the pressure of the processing steam andthe latter being at the lower pressure of the ejection steam. Becausethis pressure differential is relatively small, elaborate means, such asuse of an injector similar to Injector A, is not required to transportthe fodder from pipe 11 to pipe 15. Although such an Injector A could beused and would perform the required transport function, such complexityis not required and would result in added, unnecessary cost.

Ejection steam, entering metering valve 14 via line 92 and ejecting thefodder material from nozzle 93 into the atmosphere, still hasconsiderable enthalpy that may be recovered by discharging nozzle 93into a chamber 103 (FIG. 2) wherein by disengaging action, as describedabove for separator 10, the ejection steam may be separated from theexpanded fodder material and be recovered to be routed, for example, toheat exchanger 70 (in a manner not shown) wherein more enthalpy may beavailable to preheat the city water. In this manner processing steamwith the same enthalpy may be provided at reduced steam boiler 64output. Such recovery and use of the ejection steam is within the scopeof the invention.

AUTOMATIC CONTROL E

During the fodder expansion operation, moisture is continually ejectedthrough restrictive opening or nozzle 93. This moisture must be in theform of high quality ejecting steam and high quality steam in the foddercreated from moisture initially present therein if a dry expanded fodderproduct is to be obtained. If some of the moisture passing through thenozzle is in the form of low quality steam, or water into which some ofthe steam has been condensed by the enthalpy absorption of the fodderand its moisture, a wet expanded fodder product requiring auxiliarydrying will result.

Control of nozzle enthalpy, that is, the number of BTU's per pound ofmoisture passing through the nozzle, at a sufficiently high level willassure a high quality level of the steam passing through the nozzle, inturn assuring that no water is passing through the nozzle to be absorbedby the fodder upon its expansion.

Assuming a constant supply of enthalpy to the apparatus via theprocessing and ejecting steam, the nozzle enthalpy as above-defined willvary inversely with the moisture content of the fodder, for, assuming aconstant flow of fodder, the wetter the fodder, the more moisture perunit time will pass through the nozzle and the available enthalpy BTU'swill be shared by more pounds of moisture, thereby reducing nozzleenthalpy.

It is, however, a feature of fodder that its moisture content variesfrom material to material and from time to time, the latter depending inpart upon climatic and growing conditions and length of time the fodderis stored before being expanded. As the fodder being used may benonhomogeneous, there is no feasible way of determining the actualmoisture of the fodder passing through the expander at any given time.If the apparatus is adjusted to provide a nozzle enthalpy assuring a dryexpanded fodder product with an assumed 15 percent moisture content,introduction of fodder with moisture content of 20 percent may reducenozzle enthalpy to a level that the expanded material will be too wet.

On the other hand, adjusting nozzle enthalpy to such a high level thatfodder of any moisture content, no matter how high, will be expandedinto a dry product is wasteful of the energy (boiler fuel) required tosupply "excess" system enthalpy when processing relatively low moisturecontent fodder, and is excessively costly at current costs of severaldollars per million BTU's per hour.

Another, less important, consideration in controlling excessive nozzleenthalpy relates to the fact that the degree of fodder expansion isgenerally related to nozzle enthalpy; the higher the nozzle enthalpy,the more the fodder is expanded. Although generally, from a nutritionalpoint of view, the more expansion the better, handling of the materialbecomes more expensive as its bulk becomes less dense. At some point,the additional nutritional benefits are more than offset by theadditional handling costs, and more savings result from a less expandedfodder.

An important feature of the invention is that nozzle enthalpy isautomatically maintained within a predetermined range regardless of themoisture content of the fodder being processed without recourse toactually measuring the fodder moisture content or nozzle enthalpy. Thelower level of the nozzle enthalpy range assures a dry expanded fodderproduct, whereas the upper level minimizes energy usage.

This predetermined nozzle enthalpy range is maintained at a first stage,in a manner described below, by automatically decreasing boiler output,or increasing boiler output to its maximum capacity, while maintaining avirtually constant flow rate of fodder through the apparatus. If nozzleenthalpy cannot be maintained at maximum boiler output, only then is theflow of fodder (and hence moisture) through the apparatus reduced.

By virtue of the thermodynamics of the system, there is a directrelationship between the steam pressure in the Pressurized Region B(more particularly in reactor 10) and the nozzle enthalpy. Assuming aconstant steam enthalpy in reactor 10, an increase in fodder moisture,which will reduce nozzle enthalpy, causes a rapid decrease in reactorpressure as enthalpy absorption increases. The converse is likewisetrue. Thus, by sensing and controlling reactor 10 pressure within arange correlated with desired nozzle enthalpy, nozzle enthalpy may becontrolled within a predetermined range.

Boiler Output and Steam Enthalpy Control

As a first level of control, pressure is maintained within apredetermined range in reactor 10 by adjusting the processing steamenthalpy to compensate for any increased or decreased enthalpyabsorption by wetter or dryer fodder in the reactor. This isaccomplished by increasing or decreasing the fuel flow to boiler 64which in turn increases or decreases boiler steam enthalpy, which inturn increases or decreases the enthalpy of the secondary processingsteam created in vaporizer 66 by the boiler steam, thereby increasing ordecreasing reactor 10 pressure.

More specifically, as shown in FIGS. 6 and 8, pressure in reactor 10 istransmitted via a pressure line 140 to a controller 141. Withincontroller 141 a Bourdon tube 142, to which pressure line 140 isattached, drives a variable resistor 143, for example a resistance pot,in one leg of a first Wheatstone bridge 144. An opposing variableresistor 145 is manually adjusted by a control 146 and is calibrated toread in psi. The output across the Wheatstone bridge is fed into a firstamplifier 147 via electrical lines 148 and 149. The amplifier transmits,via line 150, a voltage to a motor 151 of a motordriven valve 152 whichcontrols fuel flowing into boiler 64 via fuel lines 153 and 154.

When the actual reactor pressure, as sensed by line 140, issubstantially equal to the desired reactor pressure preset by control146, resistors 143 and 145 will have such relative resistance valuesthat there will be no voltage across bridge 144, and consequently therewill be no voltage signal to motor 151 of valve 152. Thus, valve 152will remain in whatever degree of openness it was in. However, when theactual reactor pressure changes, the value of resistor 143 will bechanged via Bourdon tube 142 and bridge 144 will become unbalanced, theunbalance being amplified by amplfier 147. As a result, motor 151 willopen or close the valve to an extent whereby the increased or decreasedboiler output causes the actual reactor pressure to again besubstantially at the pressure set by control 146, at which time resistor143 will be adjusted to such value by Bourdon tube 142 that there willbe no bridge output. A new fuel flow rate to boiler 64 will thus beestablished and will remain constant until reactor pressure again startsto vary.

Because of the fast response time of boiler 64 and the sensitivity ofreactor pressure to steam enthalpy, the positioning of valve 152 bymotor 151 closely follows any change in reactor pressure and thevariation between actual reactor pressure and the predetermined pressureset by control 146 never is large, except as discussed below.

In this manner, as dryer fodder is introduced into reactor 10, actualreactor pressure starts to increase. Bridge 144 becomes unbalanced byresistor 143 and valve 152 is partially closed by motor 151, reducingfuel flow to boiler 64, and hence reducing steam enthalpy to reactor 10to reduce reactor pressure, until the reactor and predeterminedpressures equalize, at which time closing of valve 152 ceases and theoutput of boiler 64 stabilizes with a stabilized boiler fuel flow.

The reverse occurs when wetter fodder is introduced into reactor 10.However, it is possible, as the boiler is normally used somewhere nearits maximum capacity (to minimize boiler size) for a typical foddermoisture content of about 15 percent, that boiler output may bemaximized by falling reactor pressure which drives valve 152 completelyopen, and reactor pressure still decreases.

It is in circumstances when boiler output is maximized and reactorpressure continues to decrease that a secondary, or back-up, control isprovided to reduce flow of the wetter fodder into the reactor.

Injection Cycling Rate and Fodder Flow Control

As previously discussed, the cyclng rate of injector actuator 35, andhence cavity 33, is dependent upon the hydraulic pressure supplied tothe actuator through solenoid valve 45, via line 44. As hydraulicpressure to the actuator increases, the actuator and cavity cycling rateincreases. Conversely, as hydraulic pressure decreases, the cycling ratedecreases. The cycling rate of cavity 33 determines the flow of fodderinto separator 5 and thence into reactor 10.

A hydraulic pressure control regulator 160 (FIG. 6), driven by a motor161, regulates hydraulic pressure to line 44 (and hence to actuator 35,through valve 45 and line 42 or 43), which pressure is supplied as by ahydraulic pump 162, via lines 163 and 164, from a hydraulic fluidsource. Opening of regulator 160 by motor 161 causes an increase ofhydraulic pressure to actuator 35. This results in an increased fodderinjection rate by cavity 33. The converse is also true.

Automatic control of regulator 160 is accomplished in a mannercompletely analogous to that for controlling fuel valve 152, and willtherefore not be described in great detail. Reactor 10 pressure issensed via a pressure line 165 and adjusts, by a second Bourdon tubesimilar to Bourdon tube 142, a variable resistor similar to resistor 143in a second bridge, similar to bridge 144, located in controller 141. Avariable resistor, similar to resistor 145, is manually adjusted by acontrol 166, which control is set at a number of psia, for example ten,below that set by control 146.

Regulator 160 is set to be fully open and pressure at the actuator is ata maximum as determined by regulator 160 at actual reactor pressuresabove that set by control 166, although there may be other means forfurther increasing hydraulic pressure at the actuator to furtherincrease the fodder injection rate, as by increasing the pressure outputof pump 162. Thus, for any unbalanced bridge condition wherein actualreactor pressure, as sensed by line 165, is greater than the pressureset by control 166, the bridge output amplified by a second amplifier,similar to amplifier 147, and fed to motor 161 via line 167 will not andcannot cause regulator 160 to open to increase pressure to actuator 35to increase fodder flow rate.

However, if reactor pressure begins falling below the pressure preset bycontrol 166, as when boiler 64 at maximum capacity cannot compensate forenthalpy consumption by very wet fodder, the second bridge, unbalancedin the opposite direction, will cause motor 161 to start closingregulator 160. This will result in a reduction of fodder flow intoseparator 5, and thence into reactor 10, thus reducing moisture flowthrough the reactor and increasing reactor pressure by reducing the rateof steam enthalpy absorption. The fast reaction time of the systemprevents any substantial decrease of reactor pressure below the pressurepreset by control 166.

Now any unbalanced second bridge condition due to reactor pressureincreasing above the pressure set by control 166 will cause motor 161 tostart opening regulator 160, it already having been partially closed bythe previous reactor pressure decrease. This opening of regulator 160,and the ensuing increased flow of fodder into the reactor, will preventthe increase of reactor pressure until such time as regulator 160 isfully open and the fodder flow rate is maximized (all this occurring atmaximum boiler output, with valve 152 fully open).

If, after this maximum fodder flow has been reestablished, reactorpressure continues to rise, as by the fodder being dryer than previousfodder, the boiler fuel control system will reassume control when thepressure preset by control 146 is exceeded by reactor pressure.

In this manner, a substantially constant nozzle enthalpy with asubstantially constant fodder flow rate is maintained for widevariations of fodder moisture content. When it is necessary to reducefodder flow to maintain nozzle enthalpy, fodder flow will automaticallybe maximized before boiler output is reduced.

EXAMPLE

The following is an example of an application of the preferredembodiment, all values being understood to be approximate. Cavity 33 ofInjector A is of a volume to hold 7.2 pounds of heavier fodder materialssuch as corn, barley and milo. The cavity is reciprocated by actuator 35at 28 cycles per minute, resulting in a fodder flow of 12,000 pounds perhour into reactor 10 through separator 5. Consistent with this fodderflow rate, screw 12 within reactor 10 is rotated at 130 rpm by motor 20.The relative sizes of the reactor and screw are such that at this rpmand fodder flow rate, the average transit time of fodder particlesthrough the reactor is one minute.

Boiler 64, at a maximum capacity of 100 horsepower, produces 4,000pounds per hour of 80 percent quality boiler steam, at a pressure of 330psia at a temperature of 426° F., with a total enthalpy of 3.5 millionBTU's per hour. This boiler steam converts 2,900 pounds per hour of citywater to 30 percent quality secondary steam in vaporizer 66. Thissecondary steam leaves separator 78 (after disengagement) at 100 percentquality and at a pressure of 180 psia and a temperature of 373° F., witha total enthalpy of 3.4 million BTU's per hour, having absorbed 1million BTU's per hour in heat exchanger 70 in being preheated while yetin the liquid state, and the remaining 2.4 million BTU's per hour invaporizer 66 in being converted from water to steam.

Within reactor 10, the 12,000 pounds per hour of fodder which, assuminga 15 percent moisture content, comprises 10,200 pounds per hour of "dry"fodder and 1,800 pounds per hour of water in the form of includedmoisture, absorbs 2 million BTU's per hour of enthalpy from the 3.4million BTU's per hour available in the processing steam. Thetemperature of the "dry" fodder is thereby raised to 373° F. and thetemperature of its included moisture is raised to 212° F. The processingsteam, in giving up the 2 million BTU's per hour, leaves reactor 10 at aquality level of 16 percent.

This 2,900 pound per hour flow of 16 percent quality processing steamexiting reactor 10 with still 1.4 million BTU's per hour enthalpy,converts, within heat exchanger 87, 1,000 pounds per hour of water intoejecting steam of 100 percent quality and at a pressure of 140 psia anda temperature of 353° F., with a total enthalpy of 1.2 million BTU's perhour.

There is thus a 40 psi drop (180 psia processing steam minus 140 psiaejecting steam) from pipe 11 to pipe 15 across metering valve 14 andalso a 20° F. temperature drop (373° F. processing steam minus 353° F.ejecting steam). As the fodder traverses the metering valve from ahigher energy region (180 psia and 373° F.) to a lower energy region(140 psia and 353° F.), enthalpy is returned to the system by the fodderand its moisture in the form of "reheat." The 10,200 pounds per hour ofdry fodder returns 102,000 BTU's per hour and the 1,800 pounds per hourof included moisture returns 88,200 BTU's per hour, for a total returnto the system of 190,200 BTU's per hour. In addition, the 1,800 poundsof included moisture delivers to the nozzle region the 583,200 BTU's perhour it absorbed in reactor 10. Thus, a total of nearly 2 million BTU'sper hour (including the 1.2 million BTU's per hour of the ejectingsteam) is delivered to, and is available at, the nozzle region. (Theenthalpy of the dry fodder is not included in this calculation, inasmuchas it leaves the nozzle with substantially the same enthalpy it broughtto the nozzle, and so neither supplies enthalpy to, nor requiresenthalpy from, the nozzle region). This 2 million BTU's per hourenthalpy at the nozzle region is divided among the 1,800 pounds per hourof moisture included in the fodder and the 1,000 pounds per hour ofejection steam, for a nozzle enthalpy of 700 BTU's per pound of moisturepassing through the nozzle. This nozzle enthalpy is sufficient toconvert the moisture passing through the nozzle into 44 percent qualitysteam, such being sufficient to produce a dry expanded fodder requiringno auxiliary drying.

Control 146 of the Automatic Control is preset at 180 psia, the desiredreactor pressure, and control 166 is preset at 170 psia, a sufficientlylower pressure than the 180 psia setting of control 146 to assure thatthe first level of control will be of valve 152 controlling fuel flow toboiler 64. The automatic control, by controlling fuel flow to the boilerand injection rate, will maintain the nozzle enthalpy within the generalrange of 450 to 750 BTU's per pound of moisture passing through thenozzle, regardless of moisture content of the fodder being processed.The lower limit of 450 BTU's per pound is such that below this enthalpylevel the expanded fodder will be too wet, and the upper level of 750 issuch that above this level more enthalpy than necessary will be suppliedat a waste of boiler fuel. The range is of sufficient width tocompensate for uncontrolled conditions such as ambient humidity.

In the foregoing example, the pressure and temperature of the processingsteam (180 psia and 373° F.) and of the ejection steam (140 psia and353° F.) are seen to be conditions of saturated, rather than superheatedsteam.

It is also seen from the example that the enthalpy of the ejection steam(1.2 million BTU's) is nearly equal to that of the processing steam asit leaves the reactor (1.4 million BTU's) but that the flow of ejectionsteam is much less than that of the ejection steam (1000 pounds per hourcompared with 2900 pounds per hour).

The amount of enthalpy delivered to the nozzle region by the ejectionsteam is thus nearly that which would have been delivered had theprocessing steam itself been used for ejection; however, the amount ofmoisture passing through the nozzle (in the form of ejection steam andmoisture in the fodder) which must share this enthalpy is very muchreduced. Thus, nozzle enthalpy (which is the number of BTU's per poundof moisture flowing through the nozzle) is greatly increased byemploying the "used" processing steam only to create an additional,lesser flow of ejection steam, rather than by employing substantiallythe full flow of processing steam to eject the fodder material. Toachieve a comparable nozzle enthalpy using the full flow of processingsteam for ejecting the fodder, as commonly done in batch processorsheretofore available, a much higher enthalpy processing steam would berequired, at a considerably greater expenditure of boiler fuel.

It is thus seen that the preferred embodiment described herein deliversa given nozzle enthalpy at a given fodder flow rate with much lessexpenditure of boiler fuel than comparable batch processors heretoforeavailable. Expressed otherwise, at a given fuel consumption and fodderflow rate, the preferred embodiment described provides a much highernozzle enthalpy.

The variable rotational speed of the screw 12 allows the transit time ofthe fodder particles through the reactor to be varied over a wide rangesuch that pre-expansion treatment of different types of fodder materialsmay be optimized. Varying the speed of rotation has the effect ofvarying the bulk density of the fodder in the reactor and thus providesfor optimum processing of fodder particles having high angles ofinternal friction which makes them resistant to flow (e.g. grain such ascorn, which has been crushed or broken before treatment). The flowcharacteristics of such material may be greatly improved and clogging ofthe apparatus thus prevented by increasing the rotational speed of thescrew 12 to decrease the material's bulk density. This allows use offodder materials which would otherwise be poorly expanded or would bewasted.

SUMMARY

A preferred embodiment has been described, and illustrated by an exampleof a particular application, for expanding fodder in a continuous flow,rather than a batch, process, and which automatically yields a productrequiring no auxiliary drying prior to its use or storage regardless ofthe initial moisture content of the fodder. A recirculating steam boilercreates, from untreated city water, the steam necessary for processingand ejecting the fodder.

It is to be appreciated that there are other applications for suchexpanders of particulate matter, and the scope of the invention islimited only by that of the appended claims.

What is claimed is:
 1. An expander for particulate fodder, comprising:a.a pressurized region in which particulate fodder is pressurized prior toexpansion into puffed form, b. injection means for introducingparticulate fodder into said pressurized region while substantialpressure is maintained in said pressurized region, whereby processing ofparticulate fodder previously introduced may be continued during theintroduction of additional particulate fodder, c. a restrictive openingthrough which the pressurized particulate fodder is ejected into aregion of pressure lower than that of said pressurized region forexpansion into puffed form, d. transport means for moving pressurizedfodder through said pressurized region to said restrictive opening, ande. means for maintaining enthalpy at said restrictive opening within apredetermined range.
 2. The expander of claim 1, wherein said injectionmeans recited in clause 1(b) comprises:a. a piston sleeve communicatingat a first region with a source of particulate fodder and at a secondregion with said pressurized region, b. at least two axially separatedpistons installed within said piston sleeve,said pistons beingmaintained in mutual spaced relationship to form a cavity there between,and c. actuator means for moving said pistons in unison within saidpiston sleeve,said actuator means including means for moving said cavityalternatively between said first region where said cavity is filled fromsaid source of particulate fodder and said second region where saidcavity empties particulate fodder into said pressurized region.
 3. Theexpander of claim 2 including means for introducing a flow ofpressurized fluid through said cavity when it is at said second region,whereby particulate fodder is swept from said cavity into saidpressurized region.
 4. The expander of claim 3 including (a) means forflowing said pressurized fluid to said pressurized region when thecavity is not at said second region, and (b) means for blocking flow ofsaid pressurized fluid to said source of particulate fodder.
 5. Theexpander of claim 1, wherein:a. steam means are provided for creating aflow of pressurized steam,said steam being introduced into saidpressurized region to heat and steam said particulate matter as it isbeing pressurized, b. said pressurized region recited in clause 1(a)includes a reactor through which said steam flows, and c. said transportmeans recited in clause 1(d) includes rotating screw means within saidreactor for transporting the particulate fodder through said reactor ina direction opposite said steam flow,said screw means transportingparticulate fodder through said reactor in a substantially continuousmanner.
 6. The expander of claim 5 wherein said steam means aresaturated steam creating means.
 7. The expander of claim 5, wherein saidrotating screw means recited in clause 5(c) is mounted for rotation on asubstantially vertical axis for transporting the particulate fodder froman inlet substantially at the bottom of said reactor upward to an outletsubstantially at the top of said reactor,said rotating screw means beingof significantly smaller diameter than the inside of said reactor toallow some particulate fodder being transported upward through saidreactor by said screw means to fall back down into said reactor forrecirculating, whereby uniform heating, steaming and pressurizing of theparticulate fodder is assured.
 8. The expander of claim 5, wherein saidsteam means recited in clause 5(a) comprises a steam boiler having afeed water source and heat exchanger means connected with said boilerand with a second water source for creating a secondary source ofprocessing steam from said second water source by use of steam from saidboiler,said steam from said boiler being recycled through said boiler,whereby boiler feed water need not be continually replenished.
 9. Theexpander of claim 8, wherein said heat exchanger means includes avaporizer connected to said boiler and said second water source forcreating said secondary source of processing steam and a separatorconnected to said vaporizer and adapted to receive said processing steamfrom said vaporizer,said processing steam being of low quality as itleaves said vaporizer, whereby precipitation within said vaporizer ofimpurities in said processing steam is minimized, said separatorincluding an inner baffle for reducing the flow velocity of said lowquality processing steam from said vaporizer to convert it into highquality steam by a disengaging process.
 10. The expander of claim 9,wherein said steam means recited in clause 5(a) includes a second heatexchanger means connected to a third source of water and adapted foraccepting the flow of said processing steam as it leaves said reactor tocreate a source of ejecting steam from said third source of water forejecting the particulate fodder from said restrictive opening forexpansion into puffed form.
 11. The expander of claim 10 wherein saidsource of ejecting steam is substantially smaller than said flow of saidprocessing steam.
 12. An expander for particulate fodder comprising:a.steam means for providing high enthalpy pressurized processing steam andejection steam, b. a pressurized region connected to receive saidprocessing steam and including means for heating, steaming andpressurizing particulate fodder by said processing steam prior toexpansion into puffed form, c. injection means for introducingparticulate fodder into said pressurized region while substantialpressure is maintained in said pressurized region, whereby processing ofparticulate fodder previously introduced may be continued during theintroduction of additional particulate fodder, d. a restrictive openingconnected to receive particulate fodder which is ejected therethrough bysaid ejection steam for expansion into puffed form, e. transport meansfor moving particulate fodder through said pressurized region to saidrestrictive opening, and f. control means for controlling the enthalpyupstream of said restrictive opening within a predetermined rangeassuring a dry expended fodder, regardless of the rate of enthalpyabsorption by the fodder material and its included moisture.
 13. Theexpander of claim 12, wherein:a. said steam means recited in clause20(a) includes a steam boiler connected to a source of boiler fuel, andan electrically driven fuel valve for controlling flow of fuel from saidfuel source to said boiler, an increase or a decrease of boiler fuelcausing a corresponding increase or decrease of steam means enthalpy,and b. said control means recited in clause 20(f) including a pressuresensing line from said pressurized region connected to a Bourdon tubeadpated for varying the resistance in one leg of a resistance bridge inaccordance with pressure in said pressurized region,said control meansalso including a control adapted for varying the resistance of anopposite leg of said resistance bridge to correspond to desired pressurein said pressurized region relating to said predetermined enthalpy rangeat said restrictive opening, said resistance bridge being connected to aamplifier wherein any unbalanced bridge output caused by pressure insaid pressurized region being different from said pressure set by saidcontrol is amplified,said amplifier being electrically connected to saidelectrically driven fuel valve to cause said valve to open or close,depending on polarity of bridge output, thereby increasing or decreasingboiler fuel and increasing or decreasing enthalpy of said steam means,until the pressure in said pressurized region and said set by saidcontrol substantially equalize, at which time said resistance bridgebecomes balanced and said amplified electrical signal to said fuel valveceases and said fuel valve stops opening or closing and boiler fuel flowis stabilized, or until said fuel valve is completely open or closed.14. The expander of claim 13, wherein:a. said injection means recited inclause 20(c) includes hydraulic actuating means for cyclically operatingsaid injector to periodically introduce fodder into said pressurizedregion,said actuating means includes a hydraulic cylinder connected to asource of pressurized hydraulic fluid and having a piston connected tosaid injector, and an electrically driven pressure regulator forcontrolling hydraulic pressure to said actuator,an increase or decreaseof hydraulic pressure causing an increase or decrease in the travelspeed of said piston and a corresponding increase or decrease in therate of fodder injection into said pressurized region, and b. saidcontrol means recited in clause 20(f) includes a second pressure sensingline from said pressurized region connected to a second Bourdon tubeadapted for varying the resistance in one leg of a second resistancebridge in accordance with pressure in said pressurized region,saidcontrol means also including a second control adapted for varying theresistance of an opposite leg of said second resistance bridge tocorrespond to a second desired pressure in said pressurized region belowthe other said pressure set by the other said control, and relating tosaid predetermined enthalpy range at said restrictive opening, saidsecond resistance bridge being connected to a second amplifier whereinany unbalanced bridge output caused by pressure in said pressurizedregion being different from said second pressure set by said secondcontrol is amplified,said second amplifier being electrically connectedto said electrically driven pressure regulator to cause said valve toopen or close, increasing or decreasing hydraulic pressure, therebyincreasing or decreasing the rate of fodder introduction into saidpressurized region until the pressure in said pressurized region andsaid second pressure set by said second control substantially equalize,at which time said second resistance bridge becomes balanced and saidamplified electrical signal to said pressure regulator ceases and saidpressure regulator stops opening or closing and hydraulic pressure tothe injector actuator stabilizes thereby stabilizing the rate of fodderintroduction into said pressurized region,said pressure regulator beingfully open at pressurized region pressures above said second pressureset by said second control, whereby opening occurs only after previousclosing resulting from pressure in said pressurized region falling belowsaid second preset pressure, this occuring only when said boiler fuelvalve is fully open to maximize steam means enthalpy and pressure insaid reactor still falls.
 15. In a particulate fodder expander having apressurized region in which particulate fodder is pressurized prior tobeing ejected into a lower pressure region where expansion of theparticles occurs as a result of rapid depressurization, the improvementcomprising:a. an injection means for introducing particulate fodder intosaid pressurized region while substantial pressure is maintained in saidpressurized region, and processing of previously introduced particulatefodder is not interrupted, said injection means including a cylinderhaving a first opening communicating with a source of particulate fodderand a second opening communicating with said pressurized region, axiallyseparated pistons in said cylinder defining a cavity therebetween, andmeans for moving said cavity between said first opening for filling withparticulate fodder and said second opening for emptying said cavity intosaid pressurized region, and b. means for transporting said particulatefodder through said pressurized region in a substantially continuousmanner.
 16. In a grain or livestock fodder expander having a pressurizedregion in which grain or livestock fodder is heated and pressurized bysteam prior to being ejected through a restrictive opening into a lowerpressure region for expansion into puffed form, the improvementcomprising:means for maintaining the enthalpy in the region of saidrestrictive opening within a range of approximately 450 to 750 BTU perpound of water passing through said restrictive opening in the form ofsteam, steam condensate and moisture contained in said grain orlivestock fodder,said means including means for maintaining pressure insaid pressurized region within a predetermined pressure rangecorresponding to said 450-700 BTU ejection region ethalpy by increasingor decreasing steam boiler fuel flow to increase or decrease steamenthalpy, and after boiler fuel flow has been maximized by varying thequantity of grain or livestock fodder introduced into said pressurizedregion.
 17. A continuous flow expander for particulate fodder material,comprising:a. steam means for creating high enthalpy, dry processing andejecting steam from available, non-boiler feed water sources,said steammeans including a steam boiler with a boiler feed water source and firstheat exchanger means connected thereto, a source of available city waterconnected to said first heat exchanger means and to a drum separator anda second heat exchanger means,said steam boiler converting boiler feedwater into boiler steam, said first heat exchanger means converting saidavailable city water into a secondary source of processing steam byenthalpy supplied by said boiler steam, said drum separator includinginternal baffles to reduce the velocity of incoming processing steambelow the disengaging velocity of vapor in the steam, whereby thequality level of said processing steam as received from said first heatexchanger means is substantially increased, said second heat exchangermeans including a heat exchanger in which processing steam creates asource of ejecting steam from available water, b. processing means forheating, steaming and pressurizing particulate fodder material prior toits expansion into puffed form,said processing means including aprocessing steam and fodder separator and a reactor connected thereto bya steam pipe and a fodder pipe,said separator including baffle means toreduce the velocity of the incoming processing steam below thedisengaging velocity of steam and fodder, whereby the fodder may exitsaid separator by said fodder pipe and the processing steam may exitsaid separator by said steam pipe, said reactor including in addition tosaid steam and fodder pipes from said separator, a fodder outlet pipeand a steam outlet line, and an internal vertical screw of smallerdiameter than the inner diameter of said reactor,said screw rotating totransparent fodder from said fodder pipe at the bottom of said reactorto said fodder outlet pipe at the top of said reactor,said smallerdiameter allowing fodder material to fall back into said reactor forrecirculating to assure uniform processing, said reactor being adaptedfor flowing processing steam from said steam pipe counter to the flow offodder material for optimum enthalpy transfer to the fodder material, c.injector means for injecting particulate fodder material into saidseparator of said processing means without reducing the pressure in saidseparator or said reactor,said injector means including a cylindricalsleeve connected at a first opening with a source of particulate foddermaterial, at a second opening with said separator of said processingmeans, at a third opening with said drum separator of said steam meansand at a fourth opening with the atmosphere, said means including afirst and second piston internally closely fitting within said pistonsleeve and in spaced relationship with each other to create a foddercarrying cavity therebetween; said means also including hydraulicactuator means connected to said pistons for cycling said cavity betweensaid first sleeve opening for filling of said cavity from said foddermaterial source and said second sleeve opening for discharging saidcavity into said separator of said processing means,said third sleeveopening being aligned with said second sleeve opening for flowingprocessing steam from said drum separator of said steam means throughsaid cavity when said cavity is at said second opening to sweep foddermaterial from said cavity into said separator of said processing means,said second piston being spool shaped with a smaller central diameterfor flowing processing steam from said third sleeve opening, around saidsecond piston, into said second sleeve opening, and into said separatorof said processing means when said cavity is not at said second opening,said first piston closing said first sleeve opening when said cavity isnot at said first opening to prevent discharge of fodder material intosaid sleeve, said cavity venting through said fourth sleeve openingafter being pressurized at a said second and third sleeve openings andbefore recommunicating with said first sleeve opening, and d. anejection nozzle connected to said fodder outlet of said reactor througha fodder material metering value valve adapted for receiving foddermaterial and connected to said second heat exchanger means of said steammeans for receiving a supply steam for ejecting the fodder material fromsaid metering valve through said nozzle into the atmosphere forexpansion into puffed form.
 18. The expander of claim 17, wherein saidejection nozzle recited in clause 30(d) comprises a supersonic nozzlewith a short flow converging region, a restrictive throat and arelatively long flow diverging region whereby supersonic expansion ofsaid ejecting steam occurs within said nozzle.
 19. The expander of claim17 including control means for automatically maintaining the enthalpy atsaid ejecting nozzle within a predetermined range which at the lowerlevel assures a dry expanded fodder and which at the upper levelprevents waste of steam enthalpy.
 20. the expander of claim 19 whereinsaid control means comprises:a. means for comparing pressure in saidreactor with a first and second preset pressure, including reactorpressure lines connected to Bourden tubes which vary a resistor in oneleg of first and second resistor bridges in accordance with reactorpressure and first and second preset pressure controls adapted to varythe resistance of opposing legs of said first and second resistorbridges, whereby said bridges are unbalanced unless said reactorpressure and said first and second preset pressures are substantiallyequal, and b. means for amplifying the output of said bridges andtransmitting the amplified output of said first bridge to operate anelectrically controlled fuel valve connected to said steam boiler and ofsaid second bridge to operate an electrically controlled pressureregulator connected to said injector actuator means,said fuel valvecontrolling fuel flow to said boiler, an increase or decrease of fuelflow increasing or decreasing the enthalpy of said processing andejecting steam and thereby increasing or decreasing reactor pressure,said pressure regulator controlling hydraulic pressure to said actuatormeans, an increase or decrease in hydraulic pressure increasing ordecreasing the cycling rate of said actuator means and therebyincreasing or decreasing the injection rate of fodder material into saidseparator of said processing means, and thereby decreasing or increasingreactor pressure,said first preset pressure being higher than saidsecond preset pressure and said pressure regulator being fully open tomaximize fodder material injection rate at reactor pressures above saidsecond preset pressure,said pressure regulator not reducing foddermaterial injection rate until said fuel valve is fully open and boilerenthalpy output is maximized.
 21. An expander for particulate fodder,comprising:a. a pressurized region in which particulate fodder ispressurized prior to expansion into puffed form, b. a recirculatingsteam boiler system including a heat exchanger means and a substantiallyclosed first circuit for circulating a flow of boiler steam to said heatexchanger means and a residual flow back to said boiler, c. a liquidsupply system including a circuit separate from said first circuit, forcreating a source of processing steam from said liquid supply by use ofsteam from said boiler, connected with said heat exchanger means to pickup heat therein and to said pressurized region, d. means for introducingparticulate fodder into said pressurized region while substantialpressure is maintained in said pressurized region, whereby processing ofparticulate fodder previously introduced may be continued during theintroduction of additional particulate fodder, e. a restrictive openingthrough which the pressurized particulate fodder is ejected into aregion of pressure lower than that of said pressurized region forexpansion into puffed form, and f. transport means for movingpressurized fodder through said pressurized region to said restrictiveopening.
 22. The expander of claim 21 wherein means is provided forseparating said secondary source of processing steam from the fodderprior to ejecting said fodder through said restrictive opening.
 23. Theexpander of claim 21 including a separate discharge source of steamconnected with said restrictive opening for ejecting fodder through saidrestrictive opening.
 24. The expander of claim 23 wherein means isprovided for separating processing steam from the fodder in saidpressurized region and transferring enthalpy therefrom to said separatedischarge source of steam without adding moisture to said restrictiveopening.
 25. The expander of claim 23 wherein means is provided forrecovering a portion of said discharge source of steam ejecting fodderfrom said restrictive opening from the puffed fodder, and means isprovided for transferring enthalpy therefrom to said second liquidsupply, thereby reducing the amount of boiler fuel required to createsaid secondary source of processing steam.
 26. The expander of claim 21wherein said pressurized region includes a separator into which saidsource of processing steam and fodder enter in parallel flow and fromwhich said source of processing steam and fodder exit in separate flows,and a reactor wherein said separate flows of processing steam and fodderexit said separator flow counter to each other.
 27. The expander ofclaim 26, wherein means is provided for separating said processing steamfrom fodder in said reactor before said fodder is transported to saidrestrictive opening.
 28. The expander of claim 26 wherein means isprovided for modifying flow of fodder in said reactor to control thebulk density of the fodder.
 29. The expander of claim 21 wherein meansis provided for sensing and controlling the pressure within saidpressurized region to permit the control of enthalpy at said restrictiveopening within a predetermined range.
 30. The expander of claim 29wherein said means for sensing and controlling the pressure within saidpressurized region includes means for varying fuel flow to said boiler,and, if necessary, for varying the flow of fodder into said pressurizedregion.
 31. The expander of claim 30 wherein said latter means isconstructed to reestablish the original fodder flow rate before flow offuel to said boiler is reduced when said flow of fodder into saidpressurized region has been reduced to control said pressure in saidpressurized region, and, when further control of said pressure in saidpressurized region is required.